G. E. Martin1, R. Boudreau1, C. Couch1, M. Edwards1, G. Erich1,2, P. Jernigan1, A. Mahdy1, A. Seitz1 1University Of Cincinnati,College Of Medicine, Department Of Surgery,Cincinnati, OH, USA 2University Of Duisburg-Essen,Department Of Molecular Biology,Essen, NORTH RHINE-WESTPHALIA, Germany
Introduction: Recurrent or “chronic” urinary tract infections (UTIs) constitute a large health burden among women in the United States, with more than one quarter of young women developing recurrent UTIs despite adequate treatment of the initial organism. Pathogenesis of recurrent UTIs is poorly understood and requires a better understanding of the urogenital tract’s innate immunity. Previous research by our group has shown that sphingosine plays an important role in the innate immunity of the lung by prevention of bacterial invasion. Other groups have shown a similar role in the skin, oropharynx and gingiva. Given sphingosine’s role in the skin and respiratory tract, we hypothesized that it is also an important part of innate immunity in the bladder, and uroepithelial cells obtained from human patients with UTIs would have decreased levels of sphingosine and increased levels of ceramide relative to uninfected patients.
Methods: Samples were obtained from patients with confirmed recurrent UTIs (infected group) and those without recurrent UTIs (control group). Uroepithelial cells were isolated from these samples and stained with anti-sphingosine, anti-ceramide, and anti-acid ceramidase antibodies. Images were obtained by scanning laser confocal microscopy and analyzed using the image analysis software Imaris. Cumulative fluorescence per cell was quantified and averages obtained for infected and uninfected patients. Cells were then stained for ceramide and acid ceramidase and also underwent analysis.
Results: Decreased sphingosine staining was noted in uroepithelial cells from the infected group with subsequent quantitative fluorescent analysis of these samples showing a 41% decrease in the fluorescence present in the infected urine samples. Uroepithelial cells from the infected group showed an increase in the intensity of ceramide staining and decreased acid ceramidase staining compared to the non-infected group.
Conclusion: This work provides evidence that the ceramide-sphingosine lipid-rheostat is altered during an active human urinary tract infection. We have shown that uroepithelial cells have decreased concentrations of sphingosine and acid ceramidase and increased concentrations of ceramide upon active infection. This pathway could provide a target for novel therapies for recurrent UTIs and potentially decrease the burden of UTIs associated with antibiotic-resistant bacteria.